Raman investigation of 1,4-cyclohexadiene in the liquid and solid state

Hagemann, Hans‐Rudolf; Bill, Hans; Joly, Daniel; Müller, Paul; Pautex, Nicole

doi:10.1016/0584-8539(85)80185-9

Cited by 9 publications

(5 citation statements)

References 19 publications

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“…The assignments for the HREELS spectrum of the chemisorbed pyridine are summarized in Table . Indeed, the vibrational features are similar to those of liquid 1,4-cyclohexadiene, implying a [4+2]-like addition of N 1 and C 3 atoms of pyridine to an adjacent adatom−rest atom pair. ,,− …”

Section: Resultsmentioning

confidence: 86%

“…Indeed, the vibrational features are similar to those of liquid 1,4-cyclohexadiene, implying a [4þ2]-like addition of N 1 and C 3 atoms of pyridine to an adjacent adatom-rest atom pair. 24,25,[30][31][32] The HREELS spectrum of pyrrole chemisorbed on the clean surface (Figure 4b) at an exposure of 3 langmuirs was also included for comparison. The detection of Si-N stretching (540 cm -1 ) and Si-H stretching (2083 cm -1 ) modes with the absence of the N-H stretching at 3384 cm -1 is due to the dissociative adsorption of pyrrole on the surface through the N-H bond cleavage.…”

Section: ' Results and Discussionmentioning

confidence: 99%

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Tuning Molecular Binding Configurations of Pyridine on Si(111)-(7×7) via Surface Modification

Zhang

Wang

et al. 2010

J. Phys. Chem. C

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To prepare functional molecular templates for the development of hybrid molecular devices, multifunctional molecules may be employed and attached onto the silicon surfaces. Due to their possible multiple binding configurations, it is challenging to achieve the exclusive selectivity for the desired configuration. In this paper we describe a feasible way to tune the binding mechanism of pyridine through the coadsorption of pyrrole on the Si(111)-(7×7) surface at room temperature. Our X-ray photoelectron spectroscopy and high-resolution electron energy spectroscopy results clearly demonstrate that pyridine bonds to the clean Si(111)-(7×7) surface in the configuration of 1,4-cyclohexadiene-like adducts on the surface via Si−C(N) di-σ-linkages. However, on pyrrole-precovered surfaces, pyridine molecules are dative-bonded to the remaining adatoms on the surface. This fine-tuning of molecular configuration via surface premodification provides flexibility in controlling the molecular attachment on silicon surfaces.

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Section: Resultsmentioning

confidence: 86%

Section: ' Results and Discussionmentioning

confidence: 99%

Tuning Molecular Binding Configurations of Pyridine on Si(111)-(7×7) via Surface Modification

Zhang

Wang

et al. 2010

J. Phys. Chem. C

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“…The observation of Si−C (615 cm -1 ) and Si−N (495 cm -1 ) together with the coexistence of C sp2 −H (3045 cm -1 ) and C sp3 −H (2895 cm -1 ) stretching modes seems to suggest the formation of di−σ bonded pyridine. The detailed assignments of vibrational signatures of di−σ bonded pyridine on Si(100) at 350 K are listed in Table , together with the vibrational frequencies of liquid 1,4-cyclohexadiene. − The close resemblance between chemisorbed pyridine at 350 K and 1,4-cyclohexadiene further supports the σ-bonding nature of state B and implies the formation of a [4+2]-like cycloadduct through the N atom and its opposite C atom. The absence of Si−H peak in vibrational spectra for chemisorbed pyridine on Si(100) at temperatures ≤350 K clearly indicates the molecular adsorption nature without the cleavage of C−H bonds.…”

Section: Resultsmentioning

confidence: 90%

Dative and Di−σ Binding States of Pyridine on Si(100) and Their Thermal Stability

et al. 2003

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The chemical binding of pyridine on Si(100) has been studied using thermal desorption spectroscopy (TDS), X-ray phototelectron spectroscopy (XPS), high-resolution electron energy loss spectroscopy (HREELS), and DFT theoretical calculations. XPS results show two chemisorption states of pyridine with N 1s binding energies at 398.8 and 401.8 eV, attributable to the [4+2]-like cycloadduct with two σ-linkages of Si-N 1 and Si-C 4 , and the dative-bonded pyridine through the lone pair electrons of its N atom, respectively. These observations were further confirmed in our vibrational studies. The formation of a dative bond between pyridine and Si(100) demonstrates a new approach for the chemical attachment of unsaturated organic molecules on the Si surface. The 1,4-dihydropyridine-like cycloadduct formed at 350 K can be considered as a template for further modification and functionalization of Si surfaces or as an intermediate for syntheses in a vacuum.

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“…Therefore, these observations show that state B is a cycloadduct via the rehybridization of the C sp 2 atom and N atom, forming covalent Si−C and Si−N σ linkages, suggesting the possible [2 + 2]-like addition at N 1 and C 1 or [4 + 2]-like addition at N 1 and C 3 . The similarity in vibational features of state B (Figure b) with those of the [4 + 2]-like cycloadduct of benzene on Si(111)-7 × 7 25 and liquid 1,3-cyclohexadiene − implies a [4 + 2]-like addition of N 1 and C 3 atoms of pyridine to an adjacent adatom−rest atom pair.…”

mentioning

confidence: 90%

Si−C(N) σ Linkages and N → Si Dative Bonding at Pyridine/Si(111)-7 × 7

Feng

Lai

2003

Langmuir

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We experimentally demonstrated that pyridine/Si(111)-7 x 7 can act as an electron donor/acceptor pair as a result of the charge transfer from the electron-rich N atom of pyridine to the electron-deficient adatom of the Si surface, evidenced by the upshift of 1.8 eV (state A) for the N(1s) core level upon the formation of a datively bonded complex compared to physisorbed molecules. Another state (B) whose N(1s) binding energy downshifts by 1.2 eV was assigned to an adduct through Si-C and Si-N covalent linkages, formed via a [4 + 2]-like addition mechanism on Si(111)-7 x 7. Binding molecules through the formation of the dative bond resulted from significant electron transfer opens a new approach for the creation of Si-based molecular architectures and modification of semiconductor interfacial properties with unsaturated organic molecules.

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Raman investigation of 1,4-cyclohexadiene in the liquid and solid state

Cited by 9 publications

References 19 publications

Tuning Molecular Binding Configurations of Pyridine on Si(111)-(7×7) via Surface Modification

Tuning Molecular Binding Configurations of Pyridine on Si(111)-(7×7) via Surface Modification

Dative and Di−σ Binding States of Pyridine on Si(100) and Their Thermal Stability

Si−C(N) σ Linkages and N → Si Dative Bonding at Pyridine/Si(111)-7 × 7

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